Question on Blockr QR square

When I put in my PPC public address into Blockr, it shows a QR square

The QR square is not the same as the one as produced by the paper wallet generator

When I pressed the refresh button (on Blockr) the QR square changes into another one

I assumed there would be one QR square per address - so, what does the different and changing QR square on Blockr refer to?